Cardiovascular system

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Questions and Answers

What is the primary function of the alveoli in the lungs?

To transport oxygen-rich blood to the body

To produce surfactant to reduce surface tension

To protect the lungs from pathogens

To facilitate gas exchange between air and blood (correct)

What role does surfactant play in the alveoli?

It aids in transporting carbon dioxide to the alveoli

It increases the thickness of the alveolar wall

It helps filter out dust and pathogens

It prevents alveoli from collapsing by lowering surface tension (correct)

Which structure assists in creating intrapleural pressure in the thoracic cavity?

Expansion of the alveoli

Contraction of intercostal muscles

Diaphragm contraction

Surface tension between the pleura (correct)

What happens to intrapulmonary pressure during expiration?

It increases and air flows out of the lungs. Signup and view all the answers

How does the mechanism of inhalation affect lung volume?

Lung volume increases due to thoracic cavity expansion Signup and view all the answers

Which blood vessels carry oxygen-poor blood to the lungs?

Pulmonary arteries Signup and view all the answers

Which muscles are involved in maximum inspiratory effort?

Erector spinae, pectoralis minor, scalene, and sternocleidomastoid muscles Signup and view all the answers

How is vital capacity defined?

The maximum volume of air inhaled and exhaled. Signup and view all the answers

What role do the abdominal wall muscles play during forced expiration?

They push upward against the diaphragm to increase thoracic pressure. Signup and view all the answers

What type of cells defend the lungs against inhaled pathogens?

Dust cells (macrophages) Signup and view all the answers

What is the tidal volume in a healthy adult at normal, relaxed breathing?

500 mL Signup and view all the answers

What happens to the thoracic cavity during exhalation?

The volume decreases and pressure increases Signup and view all the answers

What is a key characteristic of the respiratory membrane that facilitates gas exchange?

It has a large surface area and is extremely thin Signup and view all the answers

What instrument is used to measure ventilation?

Spirometer Signup and view all the answers

Which of the following actions typically requires forced expiration?

Heavy exercise or blowing out candles Signup and view all the answers

What causes the decrease in thoracic cavity volume during expiration?

Relaxation of the diaphragm and rib cage movement inward Signup and view all the answers

What is the approximate increase in volume of air during forced inspiration beyond the tidal volume?

3,000 mL Signup and view all the answers

How much air remains in the lungs after a forced expiration is known as?

Residual volume Signup and view all the answers

Which of the following best describes the role of the phrenic nerve?

Carries impulses to the diaphragm Signup and view all the answers

What is the primary physiological trigger for hyperpnea?

Increased levels of carbon dioxide and hydrogen ions Signup and view all the answers

What prevents overexpansion of the lungs during deep breathing?

Hering-Breuer reflex Signup and view all the answers

What percentage of tidal volume actually reaches the alveoli?

70% Signup and view all the answers

Which brain structure primarily controls the normal quiet breathing known as eupnea?

Medulla oblongata and pons Signup and view all the answers

Where are the chemoreceptors that monitor blood oxygen levels primarily located?

Carotid arteries and aorta Signup and view all the answers

What is the primary mechanism by which oxygen is transported in the blood?

Bound to hemoglobin in red blood cells Signup and view all the answers

During gas exchange in the lungs, where does oxygen flow when concentrations differ?

From the alveoli to the blood Signup and view all the answers

What factors increase the release of oxygen from oxyhemoglobin in the tissues?

Increased acidity and temperature Signup and view all the answers

What is the primary form in which carbon dioxide is transported in the blood?

As bicarbonate ions Signup and view all the answers

In internal respiration, oxygen moves from which area to where?

From blood to tissues Signup and view all the answers

What percentage of oxygen in the blood is transported dissolved in plasma?

2-3% Signup and view all the answers

How is carbon dioxide mainly transported by hemoglobin in the blood?

As carbaminohemoglobin Signup and view all the answers

What occurs when the concentration of oxygen decreases?

Breathing rate and depth increase Signup and view all the answers

What happens to pitch when the tension on the vocal cords increases and the glottis narrows?

Pitch increases Signup and view all the answers

What is the primary function of the epiglottis?

Prevents food from entering the larynx Signup and view all the answers

Which structure creates a patent airway and allows the esophagus to expand when swallowing?

C-shaped cartilaginous rings Signup and view all the answers

What distinguishes the primary bronchi in the lungs from each other?

The right primary bronchus serves three lobes while the left serves two Signup and view all the answers

Which part of the lung helps create surface tension and holds the lungs open against the chest wall?

Pleural fluid Signup and view all the answers

What characterizes bronchioles in the respiratory system?

They possess a well-developed smooth muscle layer Signup and view all the answers

At puberty, which changes are most pronounced in males regarding the voice?

More prominent Adam's apple and deeper voices Signup and view all the answers

What effect does smoking have on the mucociliary escalator in the trachea?

It destroys the cilia Signup and view all the answers

Study Notes

Alveoli Function

Primary function: Gas exchange - Oxygen enters the blood and carbon dioxide exits the blood.
Surfactant: A lipoprotein that reduces surface tension within alveoli, preventing collapse.

Intrapleural Pressure

Structure: Parietal pleura, which lines the thoracic cavity.
Function: Creates a negative pressure that keeps lungs inflated.

Expiration

Intrapulmonary pressure: Increases during exhalation.

Inhalation

Mechanism: Increases lung volume by expanding the chest cavity.

Oxygen-Poor Blood

Vessels: Pulmonary arteries carry oxygen-poor blood from the heart to the lungs.

Maximum Inspiratory Effort

Muscles involved: Diaphragm, external intercostals, scalenes, sternocleidomastoid.

Vital Capacity

Definition: The maximum volume of air that can be exhaled after a maximal inspiration.

Forced Expiration

Abdominal wall muscles: Assist in expelling air from the lungs by increasing abdominal pressure.

Lung Defense Mechanisms

Cells: Alveolar macrophages engulf and destroy inhaled pathogens.

Tidal Volume

Healthy adult, normal breathing: Approximately 500 ml.

Exhalation

Thoracic cavity change: Decreases in volume.

Respiratory Membrane

Key characteristic: Thin to facilitate gas exchange.

Ventilation Measurement

Instrument: Spirometer.

Forced Expiration Requirement

Action: Coughing, forcefully blowing out air.

Thoracic Cavity Volume Decrease

Cause: Relaxation of diaphragm and external intercostal muscles.

Forced Inspiration Increase

Volume: Approximately 1500-2000 ml.

Residual Volume

Definition: The volume of air that remains in the lungs after a forced expiration.

Phrenic Nerve Function

Role: Innervates the diaphragm, controlling breathing.

Hyperpnea Trigger

Primary trigger: Increased demand for oxygen, typically due to exercise.

Lung Overexpansion Prevention

Mechanism: Stretch receptors in the lungs signal the brain to inhibit further inhalation.

Alveolar Air Volume

Percentage of tidal volume: Approximately 70-90%.

Eupnea Control

Brain structure: Medulla oblongata.

Blood Oxygen Level Monitoring

Location: Carotid and aortic bodies.

Oxygen Transport

Primary mechanism: Bound to hemoglobin in red blood cells.

Oxygen Flow During Gas Exchange

Direction: From alveoli into blood capillaries, where oxygen levels are lower.

Oxygen Release from Oxyhemoglobin

Factors: Increased temperature, lowered pH, increased carbon dioxide levels.

Carbon Dioxide Transport

Primary form: Disolved in plasma (7%); bound to hemoglobin (23%); as bicarbonate ions (70%).

Internal Respiration Oxygen Movement

Direction: From blood capillaries to tissue cells.

Dissolved Plasma Oxygen

Percentage: 1.5%.

Carbon Dioxide Transport by Hemoglobin

Mechanism: Bound to globin portion of hemoglobin.

Oxygen Concentration Decrease

Result: Increased breathing rate and depth.

Vocal Cord Tension and Pitch

Effect: Highers the pitch.

Epiglottis Function

Role: Covers the opening of the larynx during swallowing, preventing food from entering the trachea.

Patent Airway and Esophageal Expansion

Structure: Pharynx, a muscular tube.

Primary Bronchi Distinction

Characteristic: Right bronchus is wider and shorter than the left.

Lung Surface Tension and Openness

Structure: Pleural fluid, which is located between the visceral and parietal pleura.

Bronchioles

Characteristics: Smaller than bronchi; lack cartilage support; walls contain smooth muscles.

Male Voice Changes at Puberty

Changes: Larynx enlargement and vocal cord lengthening, resulting in deeper voice.

Smoking Effect on Mucociliary Escalator

Impact: Damages cilia, impairing the ability to clear mucus and debris from the trachea.

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